1. Field of the Invention
The invention relates to a semiconductor structure and a method for manufacturing the same. More particularly, the invention relates to a thin film transistor (TFT) structure and a method for manufacturing the same.
2. Description of Related Art
The most common liquid crystal display (LCD) is mainly composed of a thin film transistor (TFT) array substrate, a color filter substrate, and a liquid crystal layer sandwiched between the two substrates. In a conventional TFT array substrate, amorphous silicon (α-Si) TFT or low temperature polysilicon TFT often serves as a switch device of each sub-pixel. Generally, the TFT at least has a gate, a source, a drain, a channel layer, and so on; and conductivity of the channel layer may be changed by controlling a voltage on the gate, such that the source and the drain are electrically conducted (ON) or electrically insulated (OFF). In addition, an n-doped or p-doped ohmic contact layer is often formed on the channel layer, so as to reduce the contact resistance between the channel layer and the source or between the channel layer and the drain. The channel layer of the conventional TFT is mostly made of α-Si or polysilicon.
The resultant TFT however requires high manufacturing temperature regardless of the material (α-Si or polysilicon) of the channel layer; therefore, the existing manufacturing process of low-temperature polysilicon and α-Si may cause damages to a flexible substrate, an adhesion layer, or other components. The damages to these components may further pose a negative impact on device characteristics of a display. In addition, both the carrier mobility and the reliability of the α-Si TFT are not sufficiently satisfactory, which considerably restricts the application range of the α-Si TFT.